WO1997001117A1

WO1997001117A1 - Light reflection plate

Info

Publication number: WO1997001117A1
Application number: PCT/JP1996/001667
Authority: WO
Inventors: Akira Kabumoto; Naoki Yoshida; Masayasu Ito; Mitsunori Okada
Original assignee: The Furukawa Electric Co., Ltd.
Priority date: 1995-06-23
Filing date: 1996-06-18
Publication date: 1997-01-09
Also published as: DE69624077D1; TW340194B; DE69624077T2; KR970705766A; EP0778477A4; US5844731A; EP0778477B1; KR100383431B1; EP0778477A1

Abstract

A light reflection plate which is made of a thermoplastic polyester foamed body containing fine cells having a mean cell diameter of not greater than 50 νm, a thickness of at least 200 νm and a specific gravity of not greater than 0.7, and which has a high diffuse reflection factor of visible rays without adding a pigment or fine particles that improve scattering performance of light.

Description

I! IJ booklet

¾ Name of Iri j

Light reflecting plate surgery

The wood pi sword is used as a light box for liquid display I or a light reflector suitable for lighting fixtures such as light and heat lamps. Background technology

In the sidelight type liquid product display device, in order to obtain the function as a meta-light source, a light box with a structure as shown in Fig. 1 is generally used. As shown by K 1, a light reflection plate 1, a light guide plate 2, and a light transmission / diffusion plate 3 are provided in a stacked manner, and a lamp 4 is provided in these layers. The light of the lamp /! Is guided to the light guide plate 2 and finally exits to the display through the light transmission / diffusion plate 3 while repeatedly undergoing decaying reflection at the boundary between the light guide plate 2 and the light reflection plate 1. . As described above, in order to cause diffuse reflection in the boundary between the light guide plate 2 and the light reflection plate 1, the following method is used. For example, a method of printing a pattern that causes diffuse reflection in the lower part of the light guide plate 2 (boundary to the light reflection plate 1) is a method in which a predetermined pattern is printed between the light guide plate 2 and the light reflection plate 1. There are a method of forming a film, a method of forming a fine convex on the bottom of the light guide plate 2, and the like.

Further, since the light reflecting plate 1 is required to have a high light reflectance, the following materials are conventionally used. An example For example, a light reflecting plate is known in which a metal mirror li !! is formed by depositing a metal deposition film on a surface U of a metal or the like. However, since the light reflecting plate that reflects the mirror is hard to cause diffuse reflection, the light ft going to the display ιίιί is rather small. There are also light reflectors made of films containing | '1 color pigments such as titanium oxide. In the light reflecting plate made of this film, it is necessary to increase the amount of the pigment to suppress the leakage of light to the background, but the color added to the film is Pigments absorb light of a specific wavelength, and the more light they are added, the greater the loss of light cannot be ignored and the lower the reflectance.

In addition, Japanese Patent Application Laid-Open No. 2966819 discloses a light reflecting plate made of a polyester film having fine bubbles. In addition, a polyester film containing these fine bubbles is laminated with another polyester film in which calcium carbonate or silica particles having no light absorption are dispersed. A light reflection plate made of a film is also shown. In this case, the polyester film containing microbubbles disperses the incompatible polymer in the polyester block and wraps it around the insoluble polymer particles when it is uniaxially or biaxially extended. Manufactured by forming voids (bubbles). It is difficult to uniformly disperse the incompatible polymer in the polyester. For this reason, the dispersion of bubbles in the polyester is not uniform, and light cannot be sufficiently diffusely reflected. In addition, since the thickness of the film is reduced to less than 200 μin, the amount of light leaking to the back of the film increases. As a result, the file Films are difficult to achieve satisfactory reflectivity. Therefore,

[-In order to obtain a sufficient reflectivity, there is a question m that it is necessary to arrange another light reflector η on the back of the film.

Thus, for example, in the case of a shade part of an appliance, it may be required that the light reflectivity be traded. As the light reflecting plate on this river, a metal material such as a steel plate, an aluminum plate, or the like, or a light reflecting pigment is used in the surface of plastic injection molding. When a light reflecting plate made of metal material is used, the total reflectance of light is sufficiently high, but the amount of reflected light is low because of low diffuse reflection. On the other hand, in the case of a light reflecting plate in which a paint containing a light reflecting pigment is applied on the surface of plastic injection molding, there is a limit to thickening the coating film. In addition, there is a problem that the reflectivity of the light is low because the pigment body absorbs the light.

Japanese Patent Application Publication No. 6-225709 states that a transparent U such as glass, an infrared transmitting film, and a metal oxide having a thickness of 0.3 to 0.8 μin including fine bubbles (for example, oxidized A light reflection plate is described that is formed with a film made of titanium) to scatter visible light. However, in this case as well, the reflectance is as low as about 85% because the light scattering film is thin. In addition, highly efficient reflection characteristics cannot be obtained.

Therefore, the purpose of the wood invention is to use only the base material without adding pigments or fine particles that enhance the light scattering property or using other light reflectors with metal mirrors on the back. An object of the present invention is to provide a light reflection plate having excellent visible light diffuse reflectance. Disclosure of the sword

The wood-reflecting light reflector contains fine bubbles with an average cell diameter of 50 μm or less, and a thermoplastic polyester foam with a thickness of 20 () in or more and a specificity of 0.7 or less. It consists of rest.

The sushi description

m 1 is a pictorial view of the light box in the side-light type liquid crystal display element,

m is a metaphysical diagram showing an example of a light reflector of a lighting fixture river, m 3 is a metaphysical diagram showing another example of a light reflector of a lighting fixture river, and m is a lighting produced in the project of the tree invention. It is a metaphysical view showing the light reflector of the instrument river.

BEST MODE FOR CARRYING OUT THE INVENTION The following is a more detailed explanation of the tree njj.

The reason why the average cell diameter, thickness, and specific gravity of the light reflecting plate of the wooden reflecting pi-sword are defined as described above is as follows.

'If the uniform bubble diameter exceeds 50 μm, the diffused reflectance tends to decrease because the incident light penetrates into the light reflector and the number of irregular reflections at the bubble boundary decreases. . In particular, when a sheet-like light reflector is used in a light box of a liquid crystal element, the amount of light returning to the surface of the light reflector decreases due to light loss from the end of the light reflector. Therefore, the diffuse reflectance decreases. It is more preferable that the uniform cell diameter be 30 m or less. The average bubble If the% is smaller than the W light wave J¾, human light will be transmitted, so the f-uniform bubble diameter must be at least greater than the wavelength of the convergent light.

% If the thickness of the reflector is less than 2 (> () m), even if other ¾ {'] 満 is satisfied, the light leaks to the back of the light reflector ため ιί. If the thickness of the light reflecting plate is still small, it is inferior in shape retention when formed into a predetermined shape. The thickness of the light reflecting plate may be 500 μm or more More preferred

When the ratio of the light reflecting plate exceeds () .7, that is, when the bubble ratio becomes small, even if other requirements are satisfied, the light is not absorbed due to the resin absorption in the non-bubble resin portion or the light due to the transparent light reflecting plate. Light loss increases due to transmission and the like, so the diffuse reflectance decreases. In addition, it is preferable that the ratio IE of the light;

A thermoplastic polyester resin is used for the light reflection plate of the invention. Examples of thermoplastic polyester resin include polyethylene terephthalate ゃ polybutylene terephthalate „polyethylene terephthalateゃ Polybutylene terephthalate may be blended with other resins, such as polycarbonate, etc. Of these resins, polyethylene terephthalate Is the most preferred.

In the wood invention, the crystallization nucleus, the crystallization nucleus, the foaming nucleus, the antioxidant, and the electrolysis are applied to the thermoplastic polyester resin before foaming within a range that does not affect the light reflection characteristics. Prevention, UV protection | [; 剂, light stabilization, pigments, dyes, lubricants, and other various additives may be added. Of these additives, the addition of crystallization nuclei It is preferable that 'f is less than 5 tf! Fl%, more preferably 2! Fit% or less'. The dispersing power of the additive, and other resins containing these additives may be laminated.

There is no particular limitation on the method of manufacturing the light reflecting plate for the tree. However, considering sex, it is preferable to use the following method, for example. That is, a roll is formed by winding a sheet of the thermoplastic polyester and a senor to form a roll, and the roll is held in an inert gas atmosphere of Hi gas. Heating the thermal nj-type polyester sheet containing an inert gas to the polyester sheet and adding an inert gas to the polyester sheet is always heated with In this method, a roll composed of a thermoplastic polyester sheet and a separator is added to a roll of gas in a gas atmosphere. Before the inert gas is contained in the thermoplastic polyester sheet while being held at a temperature, it may be contained in the melt.

Hereinafter, a method for producing the light reflecting plate of the present invention will be described in more detail.

(1) First, a roll is formed by winding a thermosetting polyester sheet and a senorator together. The separator used here has a space through which the inert gas and, if necessary, the organic solvent that flows into and out of the til, and the inert gas penetrates into the head. Anything that can be ignored. As the separator, a resin nonwoven fabric or a metal net is particularly suitable. Poly resin is a non-woven fabric made of resin A resin made of a resin or a nylon resin is preferable. In addition, a nonwoven fabric made of a polyester-based resin can be suitably used as long as the fibers are intermingled and the inert gas does not easily permeate. Metal nets are generally referred to as wire crosses, in which the vertical and horizontal lines are woven in a weave pattern such as a weave, a wavy weave, a plain tatami weave, and a loose weave. It is preferable that the braid is woven in the 0 direction. The material is iron, copper, aluminum, titanium, or the power of these alloys to be suitable. Considering the above, stainless steel is more suitable. On the other hand, it is preferred that the thermoplastic polyester sheet be uninterrupted. This is because if the thermoplastic polyester sheet is interposed, the gas force will not sufficiently penetrate into the sheet, and it will not be possible to obtain the desired foam sheet. It is.

When the sheet contains an organic solvent, the crystallinity of the thermoplastic polyester sheet can be increased to 30% or more. As a result, the rigidity of the sheet is increased to iff, so that traces of separators do not easily remain on the sheet surface, and the time of inert gas penetration can be reduced. Note that, depending on the rare type of separator, there may be no trace of the separator left on the sheet surface, so that the treatment for containing the organic solvent is necessarily required. Not necessarily. However, from the viewpoint of shortening the gas permeation time, it is preferable to carry out the treatment for containing the organic solvent.

Organic solvents that can be used to increase the yield of resin sheets include benzene, toluene, methylethylketone, ethylformate, acetate, acetic acid, dioxane, and m-cresol. A Examples include phosphorus, acrylonitrile, dimethyl phthalate, nitroethane, nitrometan, and benzyl alcohol. Of these, acetone is more preferred from the viewpoint of handling and economy.

As a method of incorporating the organic solvent into the roll, there is a method of immersing the roll in a mechanical bath or a method of holding the roll in a vapor bath of the organic solvent. Compared to the method of i½ ^, the method of the elderly is smaller in the amount of the organic solvent used, and has little elution of the additive added to the thermoplastic polyester sheet. Are better"

In the method in which the roll is soaked in an organic solvent, it is sufficient if the processing efficiency is several hours at room temperature and several tens of hours from fliJ. The song containing the organic solvent in the width does not increase so much. The processing time when the roll is held in the steam bath of the machine melt and the machine melt is included also depends on the rare type of resin to be foamed and the thickness of the sheet. For example, when a roll of polyethylene terephthalate is placed in a closed container that is saturated with acetone vapor at room temperature and air to penetrate acetone, the thickness of the sheet is 0.6 in in. If it is, the processing time is more than 24 o'clock and 0.9 in m, if it is more than 48 o'clock, it is enough. By such treatment, the content of aceton in the tree width is 4 to 5 m: ft%.

If the rolls contain organic solvent in advance to increase the crystallinity of the sheet, it is not necessary to increase the crystallinity by adding a large amount of inert gas. Immersion of inert gas The transit time can be shortened. For example, if '. Carbon oxide is infiltrated into a polyethylene terephthalate sheet at 60 kg / cm ² , if the sheet thickness is 0. If I, IfiJ or later [:, 0.9 in in, 2 or more questions are sufficient.

If the rolled sheet is immersed in the smelter, before the next step, the sheet is rolled up with a separate separator, and then rolled up again. A roll may be prepared in advance.

() Next, the roll formed in the following manner is placed in a high-pressure vessel, and maintained in an inert gas atmosphere W to form a foam into a thermoplastic polyester sheet. Contains an inert gas. Inert gases include helium, nitrogen, carbon dioxide, argon, etc., of which carbon dioxide is included in the thermoplastic polyester in high ft. The preferred inert gas penetration force is 30 to 70 kg / c in ² , and more preferably 50 kg / c in ² or more. The gas infiltration time should be at least one hour, and more preferably the gas should be infiltrated until it is saturated. It depends on the rare resin to be used, the type of inert gas, the penetration power and the thickness of the sheet, for example, carbon dioxide in a polyethylene terephthalate sheet. When infiltrating at 0 kg / c in ² , if the sheet thickness is 0.6 mm, the penetration time is 24 hours or more and 0.9 in m In this case, it is preferable to set the time to 96 hours or more, and under such conditions, the content of carbon dioxide in the resin is 6 to 7% by weight.

(3) Remove the roll from the high-pressure container and separate it. The foam is created by heating only the thermo-elastic polyester sheet with an inert gas while removing the heat. At this time, after removing the container from the power container, the time until foaming is determined, and the ratio St of the obtained foam break is adjusted by the cultivation.

In terms of H rest, at this time, the longer the fig, the larger the final foam. The heating temperature at the time of foaming is set to be higher than the glass transition point and lower than the melting point of the resin. Examples of the heating stage include a hot-air circulation type foam furnace, a roll bath, and a molten salt bath. From the viewpoint of handling, it is preferable to use a hot-air circulation type foam furnace, and a hot-air circulation ^ The ultimate foaming conditions in the foaming furnace are, for example, a final foaming temperature of 240 ° C. n degrees and a linear velocity such that the foaming time is 1 to 5 minutes. Thereafter, the foamed sheet obtained from the furnace is wound on a thermoforming roll adjusted to a temperature of 150 "C or more, and then cooled. To obtain a light reflector.

The light reflecting plate obtained by such a method may be provided with a pigment or fine particles for enhancing the light scattering property, or a metal substrate or the like may be disposed on the back. In addition, a diffuse reflectance of 90% or more is exhibited in the wavelength range of 400 to 1200 IIm.

The shape of the light reflecting plate of the present invention is not particularly limited. For example, the sheet obtained by the above-described method can be used as a light reflecting plate for functioning a light source of a liquid product element as a meta-light source.

Further, by forming the sheet obtained as described above into a shape that partially covers the periphery of the light source, a light reflecting plate for a lighting fixture can be obtained. . For example, this molding method For example, using a metal molder with male and female molds, the temperature of the thermoplastic polyester foam sheet is 20 () ~ 22 (). There is a method of vacuum forming under a heating condition such that the temperature becomes C.

The shape of the light reflector of the Π! Π fixture river is as shown in Fig. 2 or Fig. 3, for example. In FIG. 2, a lamp 13 is attached to the bridging portion of the light reflecting plate 11 that reflects the reflection of the p-shaped multi-state, and the periphery of the lamp 13 is used for the light reflecting plate 11. Used for reflection. In this case, the light reflection plate 11 also serves as an II holiday. Further, in the case of No. 3, a raft body 12 is further provided outside the light reflecting plate 11. The light reflecting plate 11 may have a smooth bay ||||.

Example

The following is an example of a wooden sword.

Example i ~ 4

Polyethylene terephthalate (PET) sheets of different thickness ((: (1) 312 grade, manufactured by Unitika Ltd.)) and separators Fin non-woven fabric (FT3 (0) grade, manufactured by Nippon Vilene Co., Ltd.) PET PET sheet and non-woven non-woven fabric are subjected to TE-sealing. The rolls were rolled so that there was no contact between the surfaces of the rolls, and the rolls were kept in acetone vapor for 48 hours at room temperature and atmospheric pressure. This roll was placed in a high fl-: power container, and allowed to infiltrate 6 () kg kg / cm ² of carbon dioxide for 2 hours. Remove the separator of the olefin-based nonwoven fabric. While removing P P ': T sheet only, it was supplied continuously to a hot-air circulation type foaming furnace set at 2/10 ° C so that foaming time was 1 minute, and foaming was performed. At this time, the roll was taken out of the high-pressure container to adjust the force and the time until foaming, so that the foaming ratio was adjusted.

Comparative Examples 1 to 5

Example 1 ~ /! In the same manner as described above, foamed sheets having different thicknesses, ratios and> | '

For the obtained foamed p ι ': τ sheet, the ratio _ 币:, average cell diameter, and diffuse reflectance were measured. In addition, a molded article of a foamed PET sheet was prepared and the shape retention was evaluated. Table 1 shows these results. The specific measurement method and evaluation method are as follows. The ratio was measured by the underwater displacement method.

The average bubble diameter was determined by taking an SEM photograph of the sheet's metamorphosis and measuring the diameter of the air bubbles contained within a certain volume to equalize the indentation.

The diffuse reflectance was measured with a spectrophotometer (UV-3101PC: manufactured by Toriyama Seisakusho) in the wavelength range of 4 () 0 to 1200 nm. In Table 1, the diffuse reflectance of a plate prepared by adding fine barium sulfate powder is set to 10 ()%, and the diffuse reflectance of each light reflector is shown as a relative value.

Using the foamed PET sheets obtained, a vacuum forming machine was used to form a hemispherical lighting fixture with a j-diameter of 100 in in and a depth of 70 mm as shown in Fig. 4 using a vacuum forming machine. The light reflecting plate was thermoformed. Observe the deformation by holding the obtained light reflector by hand and applying force. Then, the shape retention was evaluated.

As shown in FIG. 1, Comparative Example 1 has a thickness of 20 () / in, Comparative Examples 2 to 4 have a thickness of less than 2 () () / m, and the ratio Hi is ( .7, and the f-uniform cell diameter of Comparative Example 5 exceeds μ) 0 μin. Therefore, Comparative Examples 1 to 5 have low diffuse reflectance in the wavelength range. In contrast, Examples 1 to 4

拡散 At any wavelength of 0 (), 600, 8 () (), 1000, and 1200in, the diffuse reflectance of ί) ()% or more was obtained. Also,

% Since the foamed sheets of Examples 1 to 4 had a thickness force of 2 () 0 μin or more, the molding leaves exhibited excellent shape retention. Example 1 ~ ^! Can be suitably used as a light reflector.

Material sheet thickness Specific gravity average Diffuse reflectance (%) Shape thickness Bubble diameter

(/ im) (iim) (iim) 400nm 600nm 800ηι lOOOnm 1200 dishes Retention Example 1 900 1700 0.10 13 97.4 97.4 96.9 97.3 97.5 Good Example 2 600 700 0.67 8 94.8 94.9 94.4 94.2 93.3 Good Example 3 300 440 0.20 15 97.2 97.7 97.5 97.5 97.7 Normal Example 4 300 340 0.48 10 92.8 94.9 94.3 94.3 94.0 Normal Comparative example 1 140 180 0.64 9 87.4 90.0 89.4 89.4 88.6 Bad Comparative example 2 140 160 0.71 12 86.8 88.5 87.8 87.8 87.3 Bad Comparative example 3 50 80 0.84 11 79.9 79.2 78.0 78.0 76.3 Bad Comparative example 4 50 60 1.12 10 71.8 68.0 66.7 66.7 65.1 Bad Comparative example 5 600 1000 0.27 76 75.8 77.8 73.2 73.2 73.9 Good Good

Claims

Scope of request I

1. Light characterized by containing microbubbles less than or equal to 0 μin in thickness and comprising a foamable polyester foam having a thickness of more than 200 in and a specificity of less than 0.7. reflector.

2. The light reflecting plate according to claim 1, wherein the thermoplastic polyester foam is made of polyethylene terephthalate.

The light reflector according to claim 1, wherein the fine bubbles have a 気泡 -average bubble diameter of 30 µin or less.

A. A consultation characterized in that the thermoplastic polyester foam has a sheet-like shape.

5. The light reflecting plate according to claim 1, wherein the thermoplastic polyester foam is formed into a shape having a reflection of a river or a bay.